I Lived out in the desert in the early 1980s and they still had Party Lines out there.
Even in the late 1980s, my parents built a place on the St. Lawrence River in NY and when they had the phone installed - the newfangled one with buttons instead of the rotary - it was a party line.
That lasted at least into the early 90s.
As for the difference between the 90s and new tech ... it's kind of like the break between Steampunk and the rest of the 20th century. New suspense and mystery and occult stories can certainly be done well, with current tech, but the writing has to evolve, too.